But the DH guidance says: ‘All primary medical services contractors and NHS bodies must review their telephony arrangements to ensure that callers are not charged more than if they were calling an equivalent geographic number.’

It adds: ‘If patients are being charged more and the primary medical services contractor is already in a contract, then it is the responsibility of the primary medical services contractor to take all reasonable steps to ensure this doesn’t happen.

‘If no solution is found, then the contractor must introduce a system whereby if a caller asks to be called back, the contractor will do so at its own expense.’

A BMA spokeswoman said: 'The BMA's legal advice to practices is that if you can demonstrate you've made all reasonable steps to ensure calls are not more expensive than equivalent calls to geographic numbers, for example by showing you would incur a financial penalty if you were to change mid-contract, then as a practice you would not be expected to provide a call back service at your own expense.'